Tunable SPR coupler by flexible polymer grating

We propose an SPR (surface plasmon resonance) coupling device which can tune the coupling condition by changing a pitch of an Au grating. The Au grating was formed on a flexible polymer membrane. SPR could be coupled to the grating, and dependency of SPR dip angles on the grating pitch was investigated. It was successfully demonstrated that the SPR dip position could be tuned depending on the grating pitch change by membrane expansion on our device. Our device has also shown that the nano-scale grating pitch can be effectively controlled on a large mm-scale device.